Injustice: Gods Among Us from Warner Bros. is one of the better mobile fighting games out there. Players get to take on the roles of numerous DC Comics superheroes like Superman, Green Arrow, and Wonder Woman and beat the tar out of enemy heroes and villains, all with simple and intuitive touch controls.

The mobile game’s impressive lineup of characters, sharp graphics, and surprisingly fair free to play structure have made it quite a hit on iOS and Android. In fact, Warner Bros. announced today that Injustice has been played over one billion times across the two mobile platforms. To celebrate that milestone, all players who log in to the game from now until the weekend ends will receive 30,000 free credits. Great time to try Injustice and unlock a character or two, wouldn’t you say?

Heroes, villains, and cards

On consoles, Injustice is a one-on-one fighting game that plays a lot like Mortal Kombat. The mobile version looks and plays a lot like its big screen counterpart, though the combat has been greatly simplified. Characters walk automatically, leaving the player free to tap and swipe to perform normal and super attacks.

The mobile version of Injustice doesn’t feature a proper story mode through which to unlock characters. Instead, players simply take on numerous battles and earn credits. These credits can then be spent in the in-game store to unlock cards that represent new playable characters. Each character card can also be leveled up to make it more powerful.

If you don’t want to grind your way towards unlocking the big heroes like Batman and the Joker, you can always choose to buy credits through In-App Purchase. With Warner Bros. giving away a bunch of credits this weekend, players can get a jump on the unlocking process without having to buy a thing.